1. Field of the Invention
This application relates to anchoring systems, splicing systems and tensioning systems. More particularly, this application relates to systems and methods used to anchor, splice and/or tension elongated reinforcement members such as rods, bars, and cables. More particularly still, this application relates to anchoring, splicing and tensioning systems allowing rods, bars, or cables to be used in reinforcing new or existing structural elements.
2. The Relevant Technology
At present, tens of thousands of bridges in the United States alone have been constructed using technology and materials that are now more than fifty years old. Such bridges may, for example, be made from concrete, masonry, steel, wood, and other materials that have since the time of construction degraded and are now in need of repair before failure occurs. Indeed, many of these bridges are in need of rehabilitation as they are in shear and/or fracture critical states. Other elements besides bridges also suffer from similar conditions, including buildings, pipelines, and other infrastructure.
Various techniques have been used in the past for rehabilitation. For example, mechanical gripping anchors have been developed. These gripping anchors grip a supporting rod and are also connected to a girder or other structural element of the bridge. This provides the bridge with additional support from the rod, and can thus help in repair or rehabilitation of the bridge for shear and flexure enhancement.
Notably, such gripping anchors may be used with, for example, fibre reinforced polymer (FRP) rods. As the gripping anchors grasp on to the FRP rods, they can induce local damage to the rods by, for example, using gripping wedges that induce stress concentrations in the rod. Stress concentrations in the rods can cause failure of the various fibres that make up the rod, thus also initiating premature failure of the rod. As a result FRP rods, which have been manufactured for more than a decade, have not been used widely in post-tensioning or in pre-stressing applications because of the lack of a practical and effective anchor.
When FRP rods are used, they are therefore generally used in a near-surface mount (NSM) technique. Rehabilitation of bridges or other structures using NSM techniques can allow concrete or masonry members to have their flexural and/or shear strength reinforced with FRP rods, and includes cutting a groove in a desired direction in the concrete or masonry surface. The groove may then be filled with epoxy adhesive or a cementitious grout and the FRP rod is placed in the groove. The epoxy or grout flows around the rod to fill in the groove and thereby embeds the FRP rod therein.
Notably, such application can thus be time consuming because of the need to cut the groove in the structural element. Additionally, there is an inherent initial weakening of the structural element by cutting the groove therein. NSM also utilizes epoxy or grout and there is difficulty in controlling the thickness and consistency of the epoxy or grout largely due to this technique being performed in field conditions rather than under testing or manufacturing conditions. Moreover, inasmuch as NSM cuts grooves into the surface of the structural element, it has more limited application for strengthening other elements such as steel structural elements.
Accordingly, what is desired are anchors that can facilitate reinforcement of structural elements, and that are easy to install for existing or new construction even under field conditions, and which is usable in a variety of different applications and with many different construction materials. Preferably, such anchors minimize or eliminate damage due to concentrated stresses while also improving flexural, strength and shear capacity through shear friction. Additionally, it is desired to provide a mechanism for stressing rods, bars, cables, or other supportive elements anchored by such devices so that post-tensioning and/or pre-tensioning may be performed. It is also desired to provide a mechanism for splicing supportive elements for larger spans.